CELL SIGNALLING AND THERMOREGULATION HE (ch 11 and 40)
AP BIOLOGY
DR WEINER
Multiple Choice (2 pt each)
1. Receptor protein activation occurs when
a. ADP is phosphorylated to ATP
b. ATP is converted to cAMP
c. There is a conformational change in the receptor protein
d. The receptor protein binds to a second messenger
2. A consequence of a signaling cascade is that it
a. Supplies energy to the cell
b. Accelerates mRNA activity
c. Is less susceptible to the impact of mutations
d. Amplifies the signaling response
3. Which of the following is a likely explanation of why natural selection favored the evolution of
signals for sexual reproduction?
a. Even in the simplest organisms, sexual reproduction requires several coordinated
responses by cells
b. Multicellular eukaryotes required signals that were responded to by multiple organ
systems.
c. Cells of several different mating types needed to sort themselves to allow for self
recognition
d. Rooted plants required chemical diffusible signals that could travel throughout the
organism
4. When a neuron responds to a particular neurotransmitter by opening gated ion channels, the
neurotransmitter is serving which part of the signaling athwy?
a. A receptor
b. A relay molecule
c. A signal molecule
d. A transducer
5. Because most receptors are membrane bound proteins, which of the following is usually true?
a. They lead to changes in intracellular ion concentrations
b. They open and close in response to protein signals
c. They are only attached to one membrane surface, either interior or exterior
d. They change their conformation after binding with signal molecules
6. Since steroid hormone receptors are located intracellularly, which of the following is true?
a. The steroid/receptor complex can cross the nuclear membrane
b. The unbound steroid receptors are quickly recycled by lysosomes
c. The concentration of steroid receptors must be relatively high in most cells
d. The receptor molecules are free to move in and out of most organelles
7. Paracrine signaling
a. involves secreting cells acting on nearby target cells by discharging a local regulator
into the extracellular fluid.
b. requires nerve cells to release a neurotransmitter into the synapse.
c. has been found in plants but not animals.
d. involves mating factors attaching to target cells and causing production of new
paracrine cells.
8. From the perspective of the cell receiving the message, the three stages of cell signaling are
a. the paracrine, local, and synaptic stages.
b. signal reception, signal transduction, and cellular response.
c. signal reception, nucleus disintegration, and new cell generation.
d. signal reception, cellular response, and cell division.
9.
9. The process of transduction usually begins
a. when the chemical signal is released from the alpha cell.
b. when the signal molecule changes the receptor protein in some way.
c. after the target cell divides.
d. when the hormone is released from the gland into the blood.
10. Synaptic signaling between adjacent neurons is like hormone signaling in which of the
following ways?
a. It sends its signal molecules through the blood.
b. It sends its signal molecules quite a distance.
c. It requires calcium ions.
d. It requires binding of a signaling molecule to a receptor.
11. At puberty, an adolescent female body changes in both structure and function of several organ
systems, primarily under the influence of changing concentrations of estrogens and other
steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
a. Estrogen is produced in very large concentration and therefore diffuses widely
b. Estrogen has specific receptors in different cell types, but each cell responds in the same
way
c. Estrogen is kept away from the surface of any cells not able to bind it at its surface
d. Estrogen binds to specific receptors inside many kinds of cells, each of which has a
different response
Questions 12-13:
12. Normal breast cells have a cell surface receptor called her2 which binds a signal molecule
(epidermal growth factor). What does binding of the signal molecule to her2 stimulate?
a. Apoptosis
b. Cell division
c. Differentiation
d. Mutation
13. Some forms of breast cancer are designated her2 positive. These cells have close to 1000x more
her2 than normal cells. What would this excess of her2 result in?
a. Increased apoptosis and cell death
b. Increased cell division and cancer
c. Increased differentiation
d. Increased mutation and cancer
14. Lipid soluble signal molecules, like testosterone, cross the membranes of all cells but only
affect target cells because
a. Only target cells contain the appropriate receptor
b. Only target cells initiate the phosphorylation cascade leading to activation of the
transcription factor
c. Only target cells contain the cytosolic enzymes needed to activate the testosterone
receptor
d. Only target cells have the Y chromosome
15. When the temperature of the outside air exceeds their internal body temperature, jackrabbits
living in hot, arid lands will
a. Dilate the blood vessels in their large ears to transfer more body heat to the environment
b. Constrict their blood vessels in their large ears to reduce heat transfer of external heat to
the blood vessels in their ears
c. Increase motor movement to find a sunny area to maximize heat transfer into their bodies
d. Begin involuntary shivering of their skeletal muscles in order to generate more metabolic
heat
16. Which choice best describes a reasonable mechanism for animal structures becoming better
suited over evolutionary time to specific functions?
a. Animals that eat the mot food become the most abundant
b. Animals that restrict their food intake will become less abundant
c. Animals with mutations that give rise to effective structures will become more abundant
d. Animals with parents that continually improve their offspring’s structures will become
more abundant
17. All animals whether large or small have
a. Each living cell in contact with an aqueous medium
b. An external body surface that is dry
c. The ability to enter dormancy when resources are scarce
d. A basic body plan that resembles a two layered sac
18. As body size increases in animals
a. There is a decrease in the surface area to volume ratio
b. It becomes more difficult to conserve body warmth in cold environments
c. There is a greater variability in metabolic rate
d. Reproduction becomes limited to terrestrial environments
19. To increase the effectiveness of exchange surfaces lining the lungs and intestines, evolutionary
pressures have
a. Increased the exchange surface area with folds and branches
b. Increased the thickness of the membranes in these linings
c. Increased the volume of the cell in these linings
d. Deceased the metabolic rate of the cells in these linings
20. You are studying a large tropical reptile that has a high relatively stable body temperature. How
would you determine whether the animal is an ectotherm or an endotherm?
a. You know from it high stable body temperature that it is an endotherm
b. You know it is an ectotherm because it is not a bird or mammal
c. You subject this reptile to various temperatures in the lab and find that its body
temperature and metabolic rate match with the environmental temperature. You
conclude it is an ectotherm
d. You note that its environment has a high and stable temperature. Because it body
temperature matches the environmental temperature, you conclude it is an ectotherm
21. An overheated and sick dog has an impaired thermoregulatory response if it
a. increases its evaporative heat loss.
b. decreases its metabolic heat production.
c. increases its body temperature to match the environmental temperature.
d. increases its vasodilation in blood vessels near the skin.
22. Panting observed in overheated birds and mammals dissipates excess heat by
a. countercurrent exchange.
b. acclimation.
c. vasoconstriction.
d. evaporation.
23. The temperature-regulating center of vertebrate animals is located in the
a. medulla oblongata.
b. thyroid gland.
c. hypothalamus.
d. subcutaneous layer of the skin.
24. Positive feedback differs from negative feedback in that
a. Positive feedback benefits the organisms whereas negative feedback is detrimental
b. The positive feedback’s responses are in the same direction as the stimulus rather than
opposing it
c. Positive feedback mechanisms lack control centers while negative feedback
mechanisms have them
d. In positive feedback the response is an increase in some parameter (like body
temperature) while in negative feedback the response in a decrease
25. An example of an ectothermic organism that has few or no behavioral options when it comes to
its ability to adjust its body temperature is a
a. Terrestrial lizard
b. Honeybee
c. Marine invertebrate
d. Hummingbird
body temp celcius
26. Mice are mammals. As such, they are endotherms. They maintain internal heat metabolically.
A lizard is an ectotherm and gains body heat from the environment. Which of the following
graphs most accurately depicts the situation?
40
20
mouse
0
lizard
0
20
40
60
environmental temp celcius
body temp
a.
40
20
mouse
0
0
20
40
60
lizard
environmental temp
body temp
b.
40
20
mouse
0
lizard
0
20
40
60
environmental temp
body temp
c.
40
20
lizard
0
0
20
40
environmental temp
d.
60
mouse
27. In a survivably cold environment, an ectotherm is more likely to survive an extended period of
food deprivation than would an equally sized endotherm because the ectotherm
a. Maintains a high basal metabolic rate
b. Expends more energy per kg body mass than does the endotherm
c. Invests little energy in temperature regulation
d. Metabolizes its stored energy more readily than the endotherm
Open Ended Questions
1. If an endothermic organism spends 20% of its energy for temperature regulation, 12% during
reproduction, 3% for growth, and 15% for daily activities, Calculate the percentage of energy spent on
basal metabolism for the organism. Basal metabolism is the amount of energy expenditure while the
organism is at rest. Describe how those numbers would be different if the organism was ectothermic.
2. What would happen to the oxygen consumption for a 10 gram mammal as the environmental
temperature drops by 10 degrees C? Explain. How would an exothermic animal respond differently to
the conditions mentioned above?
3. Explain how negative feedback regulates body temperature
4. Regulation and homeostasis are key to living things
a. Explain what a feedback mechanism is and how it helps an organism maintain
homeostasis
b. Explain the difference between positive feedback and negative feedback
5. Maintaining population size is a feedback mechanism. Explain.
6. The following diagrams represent the actions of the 4 major kinds of signaling pathways.




Ligand gated ion channel
G protein
Tyrosine kinase
Intracellular
Although there are differences among the mechanisms of receptor protein actions, two
aspects of their activity are the same. In a few sentences describe the two aspects of
their mechanisms that are the same
Tyrosine kinase receptor
Ligand gated ion channel
G-protein receptor